arXiv 1005.42312010-05-23astro-ph.COgr-qchep-ph

耦合标量场宇宙学的N体模拟

N-Body Simulations for Coupled Scalar Field Cosmology

Baojiu Li, John D. Barrow

备注：: 28 pages, 14 figures. For a high resolution version see http://www.damtp.cam.ac.uk/user/bl267/Li_Barrow/N_body_coupled_scalar.pdf
发表信息：: Phys.Rev.D83:024007,2011
DOI：: 10.1103/PhysRevD.83.024007

摘要：

详细介绍了耦合标量场宇宙学模型的一致N体模拟的一般方法和数值实现，包括背景宇宙学和初始条件的产生（考虑到不同物质种类的不同耦合）.我们进行完全一致的模拟一类耦合标量场模型与逆幂律势和负耦合常数，变色龙机制不运作。我们发现，在这样的宇宙学模型中，除了背景膨胀之外，标度场势的作用可以忽略不计，并且产生的第五种力的大小与重力成正比，这证明了在一些早期的宇宙学模型中使用重新标度的引力常量G是合理的。类似模型的N体模拟。我们研究了标量耦合对非线性物质功率谱的影响，并与线性微扰计算进行了比较，以研究非线性模型偏离线性近似的地方。首次将识别引力维里化物质晕的算法应用到标量场宇宙学中，并用于测量质量函数和研究维里化物质晕的性质。我们发现，标量耦合的净效应有助于产生更多的重晕在我们的模拟箱和抑制的内部（而不是外部）的密度轮廓相比，预测的Spectada-CDM，而这种抑制减弱之间的耦合的标量场和暗物质粒子的强度增加。

英文摘要：

We describe in detail the general methodology and numerical implementation of consistent N-body simulations for coupled scalar field cosmological models, including the background cosmology and the generation of initial conditions (with the different couplings to different matter species taken into account). We perform fully consistent simulations for a class of coupled scalar field models with an inverse power-law potential and negative coupling constant, for which the chameleon mechanism does not operate. We find that in such cosmological models the scalar-field potential plays a negligible role except in the background expansion, and the fifth force that is produced is proportional to gravity in magnitude, justifying the use of a rescaled gravitational constant G in some earlier N-body simulations of similar models. We study the effects of the scalar coupling on the nonlinear matter power spectra and compare with linear perturbation calculations to investigate where the nonlinear model deviates from the linear approximation. For the first time, the algorithm to identify gravitationally virialized matter halos is adapted to the scalar field cosmology, and then used to measure the mass function and study the properties of virialized halos. We find that the net effect of the scalar coupling helps produce more heavy halos in our simulation boxes and suppresses the inner (but not the outer) density profile of halos compared with those predicted by lambda-CDM, while this suppression weakens as the coupling between the scalar field and dark matter particles increases in strength.

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